Aircraft landing gear and method

ABSTRACT

An amphibious aircraft has a tricycle landing gear that is movable between a retracted, or up, position and an extended, or down, position. Each member of the landing gear is protected in the forward direction by a hydrodynamic protector, or vane, or shoe, such as may tend to create lift when brought into engagement with water, as during landing. The landing gear protector vanes may be mounted to move with extension and retraction of the landing gear. The landing gear wheels may protrude to extend partially downwardly proud of the sole of the shoe. The landing gear actuator and transmission may operate all gear in concert. The shoes may include sacrificial wear members for ground engagement in the event of an inadvertent gear-up landing on terrain.

This application is a continuation of, and claims the benefit ofpriority of co-pending U.S. patent application Ser. No. 15/021,603 filedMar. 11, 2016, which was a US National Phase Entry Application claimingbenefit under 35 USC 371 based on PCT/CA 2014/000173 filed Mar. 5, 2014,itself based on and claiming the benefit of priority of US ProvisionalPatent Application 61/876,981 filed Sep. 12, 2013, the specificationsand drawings of all of which are incorporated in their entirety hereinby reference.

FIELD OF THE INVENTION

This invention relates to the field of amphibious aircraft and tolanding gear for aircraft.

BACKGROUND

Amphibious aircraft are designed to land either on water or on land.Amphibious aircraft may typically be of two types, namely those with apair of pontoons; and true flying boats with a water-tight hull. Forfixed-wing aircraft, whether using skis or a hull, there will be aforward, or leading, direction, and a rearward or trailing direction.

In either instance it is possible to land, or to attempt to land, afixed wing amphibious aircraft with the landing gear in an inappropriateconfiguration. That is, it is possible to make a landing on terrain withthe wheeled landing gear retracted; and it is possible to make a landingon water with the wheeled landing gear extended. One cause of accidentsin amphibious aircraft is landing in water with the wheels down. A waterlanding with wheeled gear extended may be catastrophic: as the geardescends into the water, it may tend to function as an oar or paddlethat generates a substantial overturning moment on the aircraft, such asmay tend to flip the aircraft over on its nose (if the gear plunges intothe water symmetrically) or to spin and flip the aircraft, possibly incartwheel fashion, if one wheel catches the water before the other. Ineither case the result may be very significant damage or personalinjury, or both.

Alternatively, when the aircraft lands on terrain with the wheeledlanding gear retracted, the effect may be that of a belly landing, withthe possibility of doing significant damage to the aircraft hull (orpontoons). Damage may similarly occur if one or another wheel of thelanding gear extends, while one or more other wheels remain retracted.

As amphibious aircraft may, by their nature, fly to destinations thatmay have non-optimal field conditions, retrieving a damaged aircraftafter an unintentional gear-up landing may itself become an adventure.

SUMMARY OF THE INVENTION

In an aspect of the invention there is a landing gear for an amphibiousaircraft, the landing gear has a wheel for rolling contact with alanding surface, and a deflector. The deflector defines a water-ridinghull extending predominantly forwardly of the wheel. The deflector hasan accommodation in which the wheel is mounted. The wheel extendspartially downwardly proud of the deflector.

In a feature of that aspect of the invention, the wheel is movablebetween a retracted position and an extended position, and thewater-riding bow or hull is correspondingly movable in co-operation withthe wheel. In another feature, the wheel has a foremost exposed portionand at the foremost exposed portion of the wheel a tangent to the wheel,when seen in side view has an angle of less than 45 degrees of arc fromhorizontal. In still another feature, the deflector has an openingformed therein, and the wheel protrudes through the opening. In afurther feature, the opening has a first edge portion running along afirst sidewall of the wheel, and an opposed second edge portion runningalong a second sidewall of the wheel. In still another feature, thedeflector has a first side portion, a second side portion, and a keelportion therebetween, the wheel being mounted between the first sideportion and the second side portion.

In another feature, the deflector extends at least three wheel diametersforward of the wheel. In still another feature, immediately forward ofthe wheel the deflector has a centerline slope forwardly and upwardly ofthe wheel of less than 20 degrees from horizontal. In a furtheradditional feature, immediately forward of the wheel the deflector has acenterline slope forwardly and upwardly of the wheel of less than 30degrees from horizontal when the wheel is in the extended position. Inanother feature, in the retracted position, immediately forward of thewheel the deflector has a centerline slope forwardly of the wheel thatis tangent to horizontal. In still yet another feature, the deflectorhas a sacrificial spine. In a further additional feature, thesacrificial spine is exposed and foremost, whereby in a gear-up landingthe sacrificial spine is closer to the ground than any other non-wheelstructure. In another feature the deflector forms one leg of a four-barlinkage, and the wheel is carried in a seat defining at least one otherleg of that four-bar linkage.

In another aspect of the invention there is a landing gear housing, orshell, for a landing gear of an amphibious aircraft. The landing gearhousing has a water-riding hull having a leading end and a trailing end.The water-riding hull has a leading portion, a first side portionextending upwardly, and rearwardly to one side of the leading portion,and a second side portion extending upwardly and rearwardly to anopposite side of the leading portion, the first and second side portionsbeing opposed. The leading end of the water-riding hull has a firstmounting fitting by which movably to connect the landing gear housing tofixed structure of the amphibious aircraft, the first mounting fittingaccommodating motion of the landing gear between a retracted positionand an extended position. The trailing end of the water riding hull hasa second mounting fitting for a wheel of the landing gear between thefirst and second side portions. The water riding hull has anaccommodation through which the wheel protrudes downwardly in both theretracted position and the extended position.

In a feature of that aspect of the invention, the wheel has an axis ofrotation, and the second mounting fitting orients the axis of rotationtransversely to the water riding hull. In another feature, the firstmounting fitting is a pivotal fitting having an axis of rotationconstraining the hull to angular motion, the axis of rotation of thewheel being parallel to the axis of rotation of the pivotal fitting. Inanother feature, as installed on the amphibious aircraft the landinggear housing defines one bar of a four bar linkage. In a still anotherfeature, the shell has a keel extending along the leading portionthereof. In a further feature the keel is a sacrificial wear member.

In another feature, the shell has an external surface defining anexternal surface of the amphibious aircraft during both flight and waterborne operation. In another feature, the shell has at least onehydrofoil member mounted thereto. In a further feature, the wheel andthe landing gear housing move together when the landing gear movesbetween extended and retracted positions, and the wheel protrudespartially downwardly proud of the landing gear housing in both theextended position and the retracted position.

In still yet another feature, there is a combination of the landing gearhousing and a co-operating fixed-position member of the amphibiousaircraft wherein the fixed position member and the shell form aco-operating common fairing of the aircraft. In a feature of thatcombination, the shell has at least one hydrofoil member mountedthereto. In another feature, the shell has at least a first hydrofoilmember mounted thereto, and the fixed position member has anaccommodation defined therein in which at least a portion of the firsthydrofoil when the landing gear is in the retracted position. In afurther feature, the first hydrofoil is seated in the accommodation ofthe fixed position member the hydrofoil is substantially flushtherewith. In another feature, the housing has a second hydrofoil membermounted thereto, the first hydrofoil member being axially to one side ofthe wheel, and the second hydrofoil member being to the opposite sidethereof.

In another aspect of the invention there is an amphibious aircrafthaving a wheeled landing gear for landing on a landing field, thewheeled landing gear being operable between retracted and extendedpositions. The landing gear is mounted within, and extends partiallydownwardly proud of, movable landing gear housings that definewater-engaging surfaces forwardly and laterally of the landing gear and,said landing gear housings moving together with said landing gear duringoperation.

In another feature of that aspect of the invention, the landing gear isa tricycle landing gear. In a further feature, the landing gear includesa plurality of wheels, and the landing gear includes a central actuatormounted to a transmission connected to operate all of the plurality ofwheels in concert. In another feature one of the landing gear wheels isa steerable nose gear. In an additional feature, the landing gearincludes left and right main gear; and a single transmission connectedto drive both the left and right gear from a shared actuator.

It may be understood that the various aspects and features may be mixedand matched as may be appropriate. It may also be understood that theforegoing is not intended to be an exhaustive listing of aspects andfeatures of the invention. These and other aspects and features of theinvention may be understood with reference to the description whichfollows, and with the aid of the illustrations of a number of examples.

BRIEF DESCRIPTION OF THE FIGURES

The description is accompanied by a set of illustrative Figures inwhich:

FIG. 1 is an isometric, general arrangement view of a portion of anamphibious aircraft shown in intermittent dashed line, with landing gearnose wheel and main gear housing assemblies shown in dashed lines, andlanding gear transmission assembly members shown in solid lines for thepurpose of establishing the general spatial arrangement of the variouscomponents of the aircraft;

FIG. 2a shows a side, or elevation, view of the amphibious aircraftportion of FIG. 1, with wheeled landing gear in the up or retractedposition or condition;

FIG. 2b shows a side, or elevation, view of the amphibious aircraftportion of FIG. 1, with wheeled landing gear in the down or extendedposition or condition;

FIG. 3a is an isometric, general arrangement view of an enlarged detailof a steerable nose gear of the aircraft of FIG. 1;

FIG. 3b is a side, or elevation, view of the steerable nose gear of FIG.3a in the retracted position;

FIG. 4a is an isometric, general arrangement view of an enlarged detailof the left main gear of the aircraft of FIG. 1;

FIG. 4b is a side, or elevation, view of the left main gear of FIG. 4ain the retracted position;

FIG. 5a shows an isometric, view of a main landing gear housing assemblyof the aircraft of FIG. 1 in a retracted position or condition seen frominboard, rearward and below;

FIG. 5b an isometric view of the landing gear housing assembly of FIG.5a from outboard, rearward and below;

FIG. 5c shows a trailing end view of the landing gear housing assemblyof FIG. 5a looking forward;

FIG. 5d is an outboard side view of the landing gear housing assembly ofFIG. 5 a;

FIG. 5e is an outboard side view of the landing gear housing assembly ofFIG. 5 a;

FIG. 6a shows an isometric, view of a main landing gear housing assemblyof the aircraft of FIG. 1 in an extended position or condition seen frominboard, rearward and below;

FIG. 6b an isometric view of the landing gear housing assembly of FIG.6a from outboard, rearward and below;

FIG. 6c shows a trailing end view of the landing gear housing assemblyof FIG. 6a looking forward;

FIG. 6d is an outboard side view of the landing gear housing assembly ofFIG. 6 a;

FIG. 6e is an outboard side view of the landing gear housing assembly ofFIG. 6 a;

FIG. 7a shows a perspective view of a steerable nose wheel landing gearhousing assembly of the aircraft of FIG. 1 in a retracted position asseen from one side, in front, and below;

FIG. 7b is a side view of the steerable nose wheel landing gear housingof FIG. 7 a;

FIG. 7c is a front view of the nose wheel landing gear housing of FIG. 7a;

FIG. 8a shows a perspective view of a steerable nose wheel landing gearhousing assembly of the aircraft of FIG. 1 in a retracted position asseen from one side, in front, and below;

FIG. 8b is a side view of the steerable nose wheel landing gear housingof FIG. 8 a;

FIG. 8c is a front view of the nose wheel landing gear housing of FIG. 8a;

FIG. 9a shows a simplified side view of the main landing gear of FIG. 5ain the retracted position; and

FIG. 9b shows the main landing gear of FIG. 6a in the extended position.

DETAILED DESCRIPTION

The description that follows, and the embodiments described therein, areprovided by way of illustration of an example, or examples, ofparticular embodiments of the principles, aspects or features of theinvention. These examples are provided for the purposes of explanation,and not of limitation, of those principles and of the invention. In thedescription, like parts are marked throughout the specification and thedrawings with the same respective reference numerals. The drawings maybe taken as being to scale unless noted otherwise.

The terminology used in this specification is thought to be consistentwith the customary and ordinary meanings of those terms as they would beunderstood by a person of ordinary skill in the aircraft industry inNorth America. The Applicant expressly excludes all interpretations thatare inconsistent with this specification, and, in particular, expresslyexcludes any interpretation of the claims or the language used in thisspecification such as may be made in the USPTO, or in any other PatentOffice, other than those interpretations for which express support canbe demonstrated in this specification or in objective evidence ofrecord, (for example, earlier publications by persons not employed bythe USPTO or any other Patent Office), demonstrating how the terms areused and understood by persons of ordinary skill in the art, or by wayof expert evidence of a person or persons of at least 10 years'experience in the aircraft industry in North America or equivalent.

In terms of general orientation and directional nomenclature, foraircraft described herein the longitudinal or lengthwise direction isdefined as being coincident with the fore-and-aft direction of flight ofthe aircraft in straight and level flight. In the case of a fixed wingaircraft, the longitudinal direction is parallel to the rollingdirection of the wheeled landing gear and to the keel direction of thehull or pontoons, as may be. The leading direction, or leading edge liestoward the forward direction of travel; the rearward or trailingdirection or trailing edge is oriented away from (i.e., backwardsrelative to) the normal direction of advance of the aircraft. Unlessotherwise noted, vertical, or upward and downward, are terms that usethe landing terrain (or, alternatively, undisturbed water level), as adatum. In the context of the aircraft as a whole, the terms cross-wise,lateral, spanwise, or laterally outboard, or transverse, or transverselyoutboard refer to a distance or orientation relative to the longitudinalcenterline of the fuselage, or of the landing gear nacelles or sponsonsor pontoons, as may be. The commonly used engineering terms “proud”,“flush” and “shy” may be used herein to denote items that, respectively,protrude beyond an adjacent element, are level with an adjacent element,or do not extend as far as an adjacent element, the terms correspondingconceptually to the conditions of “greater than”, “equal to” and “lessthan”.

The directions correspond generally to a Cartesian frame of reference inwhich the x-direction is longitudinal, the y-direction is lateral, andthe z-direction is vertical. Pitching motion is angular motion of theaircraft about a horizontal axis perpendicular to the longitudinaldirection. Yawing is angular motion about a vertical axis. Roll isangular motion about the longitudinal axis. Given that the aircraftdescribed herein may tend to have a longitudinal axis of symmetry, adescription of one half of the aircraft may generally also be intendedto describe the other half as well, allowing for differences betweenright hand and left hand parts. Also, it may be taken as a default thatthe structure of the aircraft is of aluminum fabrication except asotherwise shown in the illustrations or indicated in the text, althoughreinforced composite structure may also be employed. Other materials,such as stainless steel, or wood, might be also be used for somecomponents.

In this discussion it may by understood that persons of ordinary skillare familiar with the aircraft construction and maintenance in NorthAmerica, and may include aircraft maintenance engineers having knowledgeof US Department of Transportation, Federal Aviation Administrationpublication EA-AC 43.13-1A & 2A “Acceptable Methods, Techniques andPractices, Aircraft Inspection and Repair”, or any successor publicationthereof, as updated at the date of priority filing of thisspecification. This specification is to be interpreted in a mannerconsistent with that publication.

FIG. 1 shows a portion of an aircraft, 20. Aircraft 20 is an amphibiousaircraft. Although principles, aspects, and features of the inventionherein may be applied to rotary wing aircraft as may be appropriate inrespect of landing gear apparatus for use in landings with non-trivialforward approach velocity, it may be taken that in the embodiment ofFIG. 1 aircraft 20 is a fixed wing aircraft. Aircraft 20 may be ahigh-wing monoplane, with a fuselage indicated as 22 and the wingstructure indicated as 24, the join of wing structure 24 being at thetop of fuselage 22. Wing 24 extends laterally outboard to port andstarboard of fuselage 22.

Fuselage 22 of aircraft 20 may further include a lower portion 26 whichmay have formed on the underside thereof a hull 28 for use in water,hull 28 having a leading portion such as may be termed a bow, and atrailing portion, such as may be termed a stern, or step 30. Hull 28 maybe curved and, in the main portion thereof, may have a profile centrallydownwardly and rearwardly curved to a central, longitudinally extendingkeel 32. The tail 34 of aircraft 20 may extend rearwardly and generallyupwardly of hull 28.

Hull 28 may include lateral bulges 36 such as may tend to extendlaterally outboard of the lower portions of fuselage 22. Bulges 36 mayalso extend somewhat downwardly and may each define a sponson 38.Sponson 38 may include, or may have mounted thereto, a main landing gearhousing, or cowling, or apparatus, such as may be designated as maingear housing assembly 40, which, may be either left hand or right hand.Although asymmetric aircraft are known, aircraft 20 may be generallysymmetrical about its longitudinal centerline, such that the right handmain gear housing assembly is the mirror image of the left hand one, andthe description of one is the same as the other but for theirhandedness. Hull 28 may also include a nose landing gear housing, orcowling, or apparatus such as may be designated as nose gear housingassembly 42. The nose gear mounted within nose gear assembly 42 may be asteerable nose gear. The left and right hand main gear and the steerablenose gear may define a tricycle undercarriage, and, to the extent thatthey include respective main wheels 44 and nose wheel 46, provide atricycle landing gear for use on terrain, be it tarmac, hardpack, aprepared landing field, a beach, or other surface suited to wheeledmotion. The landing gear may be extended, such as for a wheeled landing;or may be retracted, such as for a water-borne landing.

Referring to FIG. 3a , nose wheel 46 of assembly 42 is mounted in aclevis or yoke 52 having a central, vertically oriented pivot shaft thatis pivotably mounted in a mating steering mount assembly 54. Steeringmount assembly 54 includes a pair of laterally spaced apart left andright side frames 56, each of which may be substantially planar, the twobeing mutually parallel. When viewed in profile, side frames 56 have agenerally four-sided shape, interrupted by a rearwardly extending arm58. Side frames 56 are held in spaced relationship the rearwardlymounted box-structure of the steering head shaft mount 60, and by aforward lateral shear web 60 mounted on, or across, the downwardly andrearwardly angled lower edge of side frames 56.

Upper and lower linkages 62 and 64 are pivotally mounted at the upperand lower forward corners of sideframes 56. Linkages 62 and 64 are ofthe same length. Each has a first end mounted to the aircraft structure,such as in the nose of the fuselage as at 66 and 68 respectively, thatfirst mounting being a pivotal mounting having a single degree offreedom, namely pivotal motion about the y-axis. The second end also haspivotal mountings having axes of rotation in the y-direction. Since therespective first ends and second ends are spaced the same distanceapart, the quadrilateral of the four bar linkage so formed (i.e., twolinkages, the main aircraft fuselage structure, and sideframes 56)defines a parallelogram such that while sideframes 56 follow the arc ofthe second ends (i.e., the ends distant from fixed structure) oflinkages 62 and 64, the angular orientation of sideframes 56 about they-axis is constant. Thus the orientation of the z-axis of the steeringstub shaft may tend to remain vertical. Steering yoke 52 has a laterallyextending tiller or arm 70 and steering linkage 72 by which nose wheel46 may be turned left and right, as appropriate.

The nose gear assembly, and therefore nose gear housing assembly 42which moves with the nose gear, is driven up and down by a nose gearactuator assembly, indicated generally as 74. Actuator assembly 74includes a main shaft, or torque tube 76 that extends laterally acrossthe fuselage (i.e., in the y-direction) between pivotal mountingsmounted to the fuselage structure, such as bushings. Torque tube 76 isable to pivot in a single degree of freedom, namely angular rotationabout the y-axis. An input arm 78 is mounted generally centrally totoque tube 76, and may be pushed or pulled to create a moment coupledriving torque tube 76 clockwise or counter-clockwise. Left and righthand output arms 80 extend forwardly and downwardly of torque tube 76 tostraddle nosewheel 46. A lateral cross-member 82 is rigidly mounted to,and across, sideframes 56, and extends laterally from either side of thelower aft-ward corner thereof. Lateral cross-member 82 may be a shaftthat is free to rotate about the y-axis. Drag links 84 extend betweenthe respective ends of lateral cross-member 82 and the distal ends ofoutput arms 80, such that when torque tube 76 turns, the ends of arms 80move clockwise or counter-clockwise, drawing (or pushing) on drag links84, thereby forcing shaft 86, (and hence sideframes 56 and nose wheel46), to follow the arc of motion of links 62, 64. Assembly 42 may alsoinclude a return spring, or counter-weight spring, 88, such as may tendto bias nose gear housing assembly 42 to the retracted position. Whennot being moved, the nose gear assembly, or actuator assembly 76, as maybe, has locks that retain the nose gear in either the up position or thedown position, with associated up-lock and down-lock indicators.

Nose gear housing assembly 42 is, not surprisingly, mounted at or nearthe nose of the aircraft. Nose gear housing assembly 42 may also have,or be, a nose gear shield, or deflector assembly, or shoe, which may beidentified generally as nose gear deflector 90. Deflector 90 ispivotally mounted to fuselage 22 at a pivot fitting location wellforwardly of nose wheel 46, as indicated at location 92, and may beco-axially mounted with either first end 66 or first end 68 of linkages62 or 64, such that deflector 90 may follow the same arc. The axis (orrespective axes) of rotation of the pivot fitting connection at location92 (be it at 62 or 64) runs horizontally cross-wise to the aircraftlongitudinal centerline. Thus any point of nose wheel landing gearhousing assembly 42 moves in an arc in a vertical plane parallel to thelongitudinal centerline (and the presumed direction of forward motion)of aircraft 20 more generally. Deflector 90 may have the form of a hullor prow, or stem, or planing surface with a central ridge or stem, suchas may tend to displace or ride over, water in the manner of a ski orplaning hull. Although deflector 90 may have an aerodynamic orhydrodynamic form, deflector 90 is not a cosmetic cowling. It has thestructural strength to support the aircraft when landing on water; it isalso intended to have structural strength to support the aircraft in anunintentional gear-up landing on terrain, should the range of deflectionon impact exceed the limits of deflection of nose wheel 46 alone whilenose wheel 46 is in the retracted position. To that end, thelongitudinal centerline of deflector 90 may have a central spine, orrib, or keel, or protector, or wear member, wear strip, such as may bein the nature of a sacrificial member or sacrificial keel 94 extendingalong the most exposed centerline portion thereof. In the event of ahard landing, or in the event of striking a floating object, sacrificialkeel 94 may tend to contact the terrain or floating object first, andskid along or over it. To either side of sacrificial keel 94 extendingobliquely rearwardly, upwardly and laterally inboard or outboard as thecase may be, are first and second side portions identified as 93. Whichterminate rearwardly in substantially vertical sidewalls 95 that seatwithin the side edges of the well in fuselage 22 that accommodates nosewheel housing assembly 42 more generally. To the extent that sacrificialkeel 94 is thereby damaged, it is intended that it may be replaced asnecessary or suitable. Deflector 90 may be attached to, or suspendedfrom, spring 88.

As can be seen, deflector 90 extends forwardly of wheel 46 on a gentlecurve that is more forwardly than upwardly, and that, at the point ofintersection of the projected curve of the hull and the tangent of theprofile of the tire is an oblique angle of perhaps something greaterthan 120 degrees. As can be seen, nose wheel 46 is mounted within nosegear housing assembly 42, such that the bulk of wheel 46 is between theinboard and outboard sides of the housing, and the lowermost cusp orportion of wheel 46 extending through the accommodation, namely aperture48, downwardly proud of the deflector centerline. In the case of asteerable nose-wheel, aperture 48 is of a shape (such as circular inplan view) to permit wheel 46 to turn. Nose gear housing assembly 42 hasa main portion that extends forwardly of wheel 46, but also sideportions that extends alongside, and outwardly and upwardly, of theaxle, and most of the sidewall of the body of wheel 46. Thus wheel 46 ismounted within nose gear housing assembly 42, generally toward therearward or trailing end thereof distant from the pivot mounting at theforward or leading end of housing 42.

In the example, the extent to which wheel 46 extends downwardly proudmay by 4-6 inches. Expressed differently, the point of intersection ofthe curves may be somewhere between the 7 o'clock and 8 o'clockpositions. Expressed differently again, the wheel may protrude proud ofthe surface a distance S, where S=D(1-Cos (Theta)), D being the outsidediameter of wheel 46 and theta being the angle (measured from the sixclock position of wheel 46) at which the wheel profile intersects thedeflector profile on the centerline. Theta may be in the range ofperhaps 15 to 65 degrees, and, in one embodiment, may be in the range of30-50 degrees. The general tangent slope at mid arc of deflector 90,indicated as alpha, may be of the order of 15-40 degrees from thehorizontal. In the embodiment shown, it may be 20-35 degrees, with thelocal tangent angle being closer to 15 or 20 degrees immediatelyforwardly of nose wheel 46, and closer to 35 or 40 degrees in theneighbourhood of forward pivot point 68. Expressed differently yetagain, deflector 90 has a length L₉₀ forwardly of the axle of nose gearwheel 46 that may be in the range of about 3-8 times the diameter ofnose gear wheel 46.

In general, deflector 90 provides a smooth lead-in-surface extendingforwardly of wheel 46 for engaging, and riding upon, water—like a ski,or hull or slipper or shoe. In some embodiments, the surface ofdeflector 90 may also extend aftward of wheel 46 in a trailing edgetail. Wheel 46 extends partially downwardly proud of the profile ofdeflector 90. The extent to which it stands downwardly proud maycorrespond to the expected deflection of the tire of wheel 46 during anormal landing, plus an allowance of extra travel, perhaps 50% ofnominal normal landing load travel. In the event that aircraft 20 shouldland on water with the nose gear extended, nose wheel 46 can onlypartially immerse itself before the aftmost portion of deflector 90 alsoengages the water. At speeds of interest, the clock-wise counter-actinglift arising from deflector 90 planing on the water may tend tocounter-act the counter-clockwise pitching moment generated byhydrodynamic drag on the exposed protruding portion of wheel 46.

As illustrated in FIGS. 7a and 8a , the forward facing surface deflector90 of housing assembly 42 defines a portion of the aerodynamic form, orfairing, of the nose of the aircraft in both the retracted and theextended conditions. As seen in FIG. 7b , in the retracted positiondeflector 90 seats flush with the aftwardly extending keel of fuselage22.

In some embodiments, aircraft 20 may have hydrofoil members 96 such asmay be mounted to the upstanding laterally spaced apart sidewalls 95 ofhousing assembly 42. In the retracted position, hydrofoils 96 seat inaccommodations 97 defined in fuselage 22, such that hydrofoils 96 aresubstantially flush with the adjacent structure and form a relativelysmooth, continuous streamline or continuous fairing surface as shown inFIGS. 7a, 7b and 7c . In the extended position of the nose gear as shownin corresponding FIGS. 8a, 8b and 8c , hydrofoil members 96 are exposedto passing water flow, and, upon contact with the water, may tend toexert a lifting force that is transmitted back through the structure tolift the nose of aircraft 20 (i.e., to give aircraft 20 a clockwiseturning moment in the side view of FIG. 7b to counter-act thecounter-clockwise over-turning moment such as may be generated by wheel46 (or wheels 44 further aft, as may be). In the embodiment shown,hydrofoil members 96 are mounted abreast of wheel 46, at a levelcomparable to, and in some embodiments slightly above, the axlecenterline of wheel 46.

FIG. 4a shows the landing gear transmission, identified generally as100. Many structural features have been omitted from this illustrationfor the purpose of making the landing gear components more easilyvisible. As with nose gear housing assembly 42, main gear housingassembly 40 (be it port or starboard) has main gear wheel 44 installedin a landing gear housing generally indicated as 102. Housing 102 has astationary upper, or main, portion 104,which is rigidly mounted tosponson 38; and a co-operating, movable, or lower portion 106, which mayinclude a pivotally mounted main gear vane, or protector, deflector, ordeflector assembly 110. The pivot mounting may be at the first, orleading, end of housing 102. Inasmuch as housing 102 may ultimatelytransmit the reactive force from the main gear to carry the aircraftstructural load, housing 102 is structurally connected to a laterallyextending spar or beam structure, indicated as 108. Structure 108 mayinclude an I-beam and a deep central frame assembly 98 as shown in FIG.4a . The ends of beam-and-frame structure 98 are cantilevers, which havea measure of vertical flex, and the main gear loads are carried at theends of the cantilevers. Main portion 104 may have an inboard wall 112,an outboard wall 114, and an upper wall or covering or cowling 116 allof which may be rigidly interconnected, and which may have a fairedaerodynamic shape. Housing 102 is mounted to the outboard margin ofsponson 38, be it port or starboard. Sponson 38 is water tight, and thebottom wall of sponson 38 forms a portion of hull 28. Housing 102 has adownwardly opening accommodation 118. Accommodation 118 is generallyrectangular, being much longer in the x-direction than wide in thetransverse y-direction, such as may be co-operatively shaped matingly towork with the generally box-shaped main gear slipper, or shoe, 120 oflower portion 106.

As seen in FIGS. 5a to 5e , and in FIGS. 6a to 6e , shoe 120 may have aninboard longitudinal wall 122, an outboard longitudinal wall 124, abottom deflector plate 126, joined together to form a generally U-shapedstructure, with side walls 124, 126 being generally vertical, paralleland spaced apart. Main gear wheel 44 is mounted between the inboard andoutboard portions or walls of deflector shoe 120. There may be lateralshear webs or shear frame braces 123 extending laterally therebetweenforward of main gear wheel 44 to maintain walls 122 and 124 in spacedparallel relationship from each other. The forward end of shoe 120 isenclosed, as where bottom deflector plate 126 is curved forwardly andupwardly to define the forward tip of the ski or slipper, or vane,however it may be called. A pivot mount is located at the foremost tipof shoe 120, being indicated as 128, and is mounted in structural loadspreading bushing assemblies in main portion 104. The axis of rotationof the pivot mounting may be horizontal and cross-wise to the verticalplane of symmetry of the aircraft centerline. Bottom deflector plate 106may be backed by reinforcements in the nature of longitudinal stringersand transverse frames suitable for maintaining its structural integrityin expected operation.

Bottom deflector plate 106 has a rearwardly located relief 107 near itstrailing end to accommodate protrusion of main gear wheel 44. As shownin FIGS. 5a and 5b, 6a and 6b , relief 107 may have the form of anaccommodation 130 which may be a rectangular opening, or it may be agenerally oval or rounded elongate opening corresponding to the shape ofthe tire of wheel 44. The opening is such as to have a first edgeportion forwardly of wheel 44, and side portions running along thesidewalls of wheel 44. Main gear wheel 44 seats, or is mounted withinassembly 40 between the sidewalls thereof, with a portion, or cusp ofwheel 44 protruding through relief 107. Since wheel 44 moves and housingassembly 40 move together, wheel 44 protrudes from plate 106 in both theextended and retracted positions of the landing gear. Bottom deflectorplate 106 may also have, or be formed to have, a lengthwise extendingkeel, 132, which may have a replaceable sacrificial wear member or skid134. Skid 134 may be made of a consumable material such as stainlesssteel. As seen in FIGS. 5d and 5e keel 132 is gently upwardly angled,being nearly horizontal at the point at which the foremost portion ofwheel 44 crosses the profile of keel 132, and is formed forwardlycurvedly with an increasing angle of slope toward the nose. As may beunderstood, in a normal landing, shoe 120 may tend to plane along thewater. In an inadvertent gear-up landing on terrain, wheel 44 maycontact the terrain first, and only to the extent that the landing isheavy will shoe 120, and, in particular skid 134, ride along theterrain. In an inadvertent gear-down landing on water, even as fullydeployed in FIG. 5e , the clockwise overturning moment due to drag onthe exposed portion of wheel 44 may tend to be counteracted by the liftgenerated in planing as soon as leading portion 136 of shoe 120immediately forward of wheel 44 begins to bear on the water surface. Theprotective presence of the slipper or shoe 120 forward of wheel 44 maytend to limit or counteract the overturning drag that can be developedby water drag on wheel 44. Further, considering FIG. 3a , to the extentthe nose gear deflector 90 may also engage the water, the counter-actinglifting force of deflector 90 planing on the water has a very longmoment arm relative to wheel 44.

The primary element of transmission 100 of FIG. 4a is a laterallyextending shaft 140 that extends outboard to both port and starboard. Atits most outboard extremity shaft 140 is connected to a co-axial outertube 142, which may be termed a torque tube. At its most inboard end,torque tube 142 terminates at a lever arm 144 that has a hollow centerto permit the passage of shaft 140. Arm 144 extends to the top end of adamper or spring-damper combination, identified as shock absorber 146.The other end of shock absorber 146 is mounted to a bushing, which isitself mounted to a load spreading bracket (not illustrated) within theframe of the fuselage or sponson. An input arm 150 is mounted to asleeve 152 on shaft 140. As may be understood, moving input arm 150clockwise and holding arm 144 stationary will cause shafts 140 and 142to wind up as two torque springs in series.

As shown in FIG. 4a , the outboard end of torque tube 142 is carried ina bearing mounted to upper portion 104 of housing 102. There may also bea central bearing at sleeve 152, and another bearing mounted abouttorque tube 142 immediately outboard of arm 144. At the outboard end oftorque tube 142 is a first pair of matched rearwardly extending armsdefining a first wishbone 154. At the tips of the legs of first wishbone154 is a cross-shaft 156 that ties the two tips together. A secondwishbone 158 with hollow shaft mounted co-axially with cross-shaft 156,and two extending legs (i.e., a fork or clevis, or wishbone) reach fromshaft 156 to axle 160 of wheel 44. The ends of axle 160 are mounted inseats or bushings that are themselves mounted to inboard wall 122 andoutboard wall 124 respectively. The assembly so described defines a fourbar linkage. That is, the first bar of the linkage is the fixedstructure of the aircraft. The second bar of the linkage, effectivelypivotally mounted to the fixed structure, is the first wishbone, 154.The third bar of the linkage is the second wishbone 158, and the fourthbar of the linkage is the deflector or slipper, or shoe, 120 which ispivotally mounted to the fixed structure of the first bar at pivot 128.That is, relative to the fixed structure of the aircraft, shoe 120defines the fixed radius arm constraining the arc of motion of wheel 46and main gear bottom deflector plate 126. Input to shaft 140 uniquelydetermines the position of first wishbone 154, and therefore also theposition of second wishbone 158 which functions as a drag link or slavelink in this mechanism. Thus wheel 44 is limited to translation in asingle degree of freedom along the circumferential arc described by theaxle bushings mounted to deflector 120. Given the relative length of thearm defined by deflector 120, and given the close to horizontalorientation of the arm, that motion is substantially, predominantly,upward-and-downward. Wheel 44 is movable between retracted and extendedpositions, as shown. There is an up-lock, and there is a down-lock, notshown. On landing, shaft 140 and torque tube 142 provide a somewhatresilient response, that response being damped by shock absorber 146.

Transmission 100 is driven between retracted and extended positions byactuator assembly 170 mounted within hull 28. Actuator assembly 170includes a motor (and motor control) 172, a gear reducer 174 driven bymotor 172; a worm drive 176 connected to the output of gear reducer 174;and a reciprocally movable actuator 178 driven by worm drive 176. Aswill be understood, driving motor 172 in a first direction will causethe jack of actuator 178 to extend, driving arm 144 clockwise with theeffect of extending the main gear; driving motor 172 in the oppositedirection will cause the jack of actuator 178 to retract, driving arm 44counter-clockwise, with the effect of retracting the main gear. Otherarrangements of drives could be used. In each case, deflector 120 moveswith the main gear, or, expressed differently, the deflector and thewheeled landing gear move together.

Sleeve 152 also carries an output interface, or output arm 180, which isconnected to a drag link 182, which drives a bell-crank 184. The outputof bell crank 184 is connected to a shock absorber 186, which in turncarries the aftmost end of a connecting rod 188. Connecting rod 188 hasa foremost end mounted to input arm 78 which drives torque tube 76 ofnose gear assembly 42. Shock absorber 186 may tend to provide a measureof damping decoupling of the nose gear from the main gear. Thus motionof actuator 178 drives all three wheels of the tricycle assembly in aco-ordinated manner up and down. In each case, the action of therespective wheel carries the associated deflector up and down as well.

Referring again to the main gear, deflector 120 protects the forwardside of main wheel 44. As noted, deflector 120 has a long and thinshape, deployed leading main wheel 44. The moving protective deflector,or vane, or shoe, may extend 2-8 wheel diameters forward of the maingear axle centerline, and, as above, it may be positioned and angled toleave exposed only a portion of main wheel 44, as seen from looking aftalong the wheel centerline.

Expressed differently, the point of intersection of the curves of theprofile of deflector plate 126 and wheel 44 may be somewhere between the7 o'clock and 8 o'clock positions. Expressed differently again, thewheel may protrude proud of the surface a distance S, where S=D(1-Cos(Theta)), D being the outside diameter of wheel 44 and theta being theangle (measured from the six o'clock position of wheel 44) at which thewheel profile intersects the deflector profile on the centerline. Thetamay be in the range of perhaps 15 to 65 degrees, and, in one embodiment,may be in the range of 30-50 degrees. The general tangent slope at midarc of deflector plate 126 may be of the order of 15-40 degrees from thehorizontal. In the embodiment shown, it may be 20-35 degrees, with thelocal tangent angle being closer to 15 or 20 degrees immediatelyforwardly of main gear wheel 44, and closer to 35 or 40 degrees in theneighbourhood of forward pivot point 68. Expressed differently yetagain, deflector plate 126 has a length L₁₂₆ forwardly of the axle ofmain gear wheel 44 that may be in the range of 2-10 times the diameterof main gear wheel 42. Deflector 126 may provide a smoothlead-in-surface extending forwardly of wheel 44 for engaging, and ridingupon, water—like a ski, or hull or slipper or shoe. Wheel 44 extendspartially downwardly proud of the profile of deflector plate. The extentto which it stands downwardly proud may correspond to the expecteddeflection of the tire of wheel 44 during a normal landing, plus anallowance of extra travel, perhaps 50% of nominal normal landing loadtravel. In the event that aircraft 20 should land on water with the maingear extended, wheel 44 can only partially immerse itself before theaftmost portion of deflector plate 126 also engages the water. At anysignificant speed, the clock-wise counter-acting lift arising fromdeflector plate 126 planing on the water may tend to counter-act thecounter-clockwise pitching moment generated by hydrodynamic drag on theexposed protruding portion of wheel 44.

In an alternate, or additional, embodiment, main gear housing assembly40 may include hydrofoil members, such as a first or outboard hydrofoilmember 190 and a second or inboard hydrofoil member 192, and, should thedeflectors not be considered sufficient, hydrofoils 190 and 192 may tendalso to generate a clockwise lifting moment tending to counteract theoverturning moment arising from hydrodynamic drag. Hydrofoils 190 and192 may be relatively small, and may have the appearance of relativelyshort “fins” extending laterally of the sponson structures respectively.Aircraft 20 may have respective outboard and inboard reliefs or rebates,or seats or accommodations 191 and 193 corresponding to hydrofoils 190and 192, such that in the retracted position of the landing gear,hydrofoils 190 and 192 are at least partially (in the case of hydrofoilmember 190) or fully (in the case of hydrofoil member 192) concealed orseated in a position that is flush with the adjacent faired structure,giving a relatively smooth streamlined form. As above, in the extendedposition of the landing gear hydrofoils 190 and 192 are fully exposed.Hydrofoils 190 and 192 may be located generally abreast of wheel 44 andset at a level near the level of the axle of wheel 44, such that in theevent that a gear-down landing is made on water, and hydrofoils 190 and192 may engage the water and begin to provide a lifting force even whilethe depth of wheel 44 in the water is relatively shallow.

In the event of a flat tire, or in the event of a gear transmissionfailure in which not all of the gear move to the selected position (beit up or down), the presence of nose deflector 90 and main geardeflector plates 126 may be such as to tend to provide a back-up skidsurface for landing on terrain.

Nose wheel 46 has two rotational degrees of freedom—namely rotationabout its axle, and pivoting rotation about its predominantly verticalsteering shaft. Motion of the nose gear between retracted and extendedpositions is restricted to a single degree of freedom along theconstrained arc of the parallelogram in the x-z plane. Deflector 90 hasa single degree of freedom of motion—namely translation in the arc inthe x-z plane associated with motion of the nose gear assemblygenerally. The up-and-down orientation of the nose gear steering shaftremains constant in the x-z plane.

Similarly, the main gear four bar linkage is constrained to motion in anx-z plane, and the wheel itself, while rotatable in the normal mannerabout its own axis of rotation to permit wheeled operation, isrestricted to the single degree of freedom of travel along the arctraced by the bushings of shoe 120 relative to pivot point 128.

The wheeled landing gear deflectors or shoes or slippers or protectors,however termed, shown and described herein are not to be confused withlanding gear “spats”. First, “spats” are aerodynamic fittings employedto reduce fixed landing gear drag that generally are not intended to,and typically do not, produce lift (aerodynamic or otherwise); the shoesdescribed herein are hydrodynamic lift members. Second, true “spats”tend to be a feature of fixed landing gear rather than retractablelanding gear. Third, “spats” are aerodynamic fairings of very lightstructure, as opposed to being structural members intended to takesubstantial dynamic loads such as landing loads. Fourth, spats tend toextend predominantly rearwardly of the axle of the wheel, with the formof a trailing edge of diminishing section to reduce rearward separationof airflow. The present hydro-dynamic deflectors or slippers or shoesextend predominantly forwardly of the gear, as opposed to aftward.

As described above, the anti-flip, or flip discouraging aspect ispassive. That is, it does not rely on pilot intervention, or onelectronic sensing or control systems to prevent landing in the wrongconfiguration. Of course, aircraft 20 may have such warning systems.However, even if they fail, the deflector may tend to work to protectagainst an overturning moment.

The deflector moves with the landing gear, and the forward facingsurface of the deflector also defines a portion of the exterior fairingof the aircraft in its normal operation in flight. That is, thedeflector is not concealed behind other structure, or inside a nacellein the retracted position, but rather forms a surface of the normalexterior of the aircraft. In the retracted position that surface may beflush with adjacent external surfaces to form a relatively smooth,streamlined form. The deflector protects its respective wheel in boththe retracted and the extended position.

Also, as described, the wheel protrudes from the deflector, or shoe,structure in both the extended and the retracted position. In bothpositions the wheel is in its rolling orientation, i.e., the axle ishorizontal and perpendicular to the line of forward motion of theaircraft. In both positions the shoe or deflector protects, or encloses,more than half of the wheel, with the sides of the shoe or deflectorextending from the downward portion thereof upwardly and rearwardly orthe axle. That is, the wheel is covered on both front and sides.

Various embodiments have been described in detail. Since changes in andor additions to the above-described examples may be made withoutdeparting from the nature, spirit or scope of the invention, theinvention is not to be limited to those details.

I claim:
 1. An amphibious aircraft, comprising a fuselage having awater-riding main hull; a set of wheeled landing gear; and first andsecond water riding shoes located to first and second lateral sides ofsaid fuselage.
 2. The amphibious aircraft of claim 1 wherein said set oflanding gear includes first and second main gear wheels mounted in saidfirst and second water-riding shoes.
 3. The amphibious aircraft of claim2 wherein said fuselage has first and second sponsons protrudinglaterally to left and right thereof, and said water-riding shoes beingmounted to said sponsons laterally outboard to either side of saidfuselage.
 4. The amphibious aircraft of claim 1 wherein said first andsecond water-riding shoes each has a respective keel.
 5. The amphibiousaircraft of claim 4 wherein each of said keels of said first and secondwater-riding shoes has a sacrificial wear member mounted therealong. 6.The amphibious aircraft of claim 2 wherein each of said water ridingshoes has a water-riding deflector extending forwardly of saidrespective main gear wheels.
 7. The amphibious aircraft of claim 2wherein said water riding first and second shoes are movable relative tosaid main hull.
 8. The amphibious aircraft of claim 2 comprising a nosewheel is mounted in a movable water-riding shoe mounted to said mainhull.
 9. The amphibious aircraft of claim 3 wherein said fuselage has aframe and a laterally extending beam to which said first and secondshoes are mounted.
 10. The amphibious aircraft of claim 1 wherein: saidamphibious aircraft is a high-winged monoplane aircraft; said main hullincludes a hull step and a high tail located upwardly and rearwardly ofsaid main step; said aircraft has a tricycle landing gear that includesa steerable nose-wheel mounted in said fuselage, and first and secondmain gear wheels mounted to said first and second water-riding shoes,respectively; said fuselage has first and second sponsons extendinglaterally to left and right hand sides thereof; said first and secondshoes are mounted laterally outboard of said fuselage to said first andsecond sponsons respectively; said first and second shoes each have awater-riding deflector located forwardly of said respective one of saidfirst and second main gear wheels; each of said water-riding deflectorshas a keel; and each of said keels has a sacrificial wear member mountedtherealong.
 11. The amphibious aircraft of claim 1 wherein first andsecond main gear wheels are mounted within said first and second shoes,respectively, and a lowermost portion of each of said first and secondmain gear wheels protrudes downwardly of said respective first andsecond shoes.
 12. The amphibious aircraft of claim 11 wherein said maingear wheels are movable between a retracted position and an extendedposition, and said respective water-riding shoes are correspondinglymovable in co-operation with said wheels.
 13. The amphibious aircraft ofclaim 12 wherein each said water-riding shoe has a respective deflector;immediately forward of said wheel said deflector has a centerline slopeforwardly and upwardly of said wheel of less than 30 degrees fromhorizontal when said wheel is in said extended position.
 14. Theamphibious aircraft of claim 13 wherein, in said retracted position,immediately forward of said respective wheel each said deflector has acenterline slope forwardly of said respective wheel that is tangent tohorizontal.
 15. The landing gear of claim 13 wherein each said deflectorforms one leg of a four-bar linkage, and said respective main gear wheelis carried in a seat defining at least one other leg of that four-barlinkage.
 17. An amphibious aircraft, wherein: said amphibious aircraftis an high-winged monoplane aircraft; said aircraft has a fuselage; saidfuselage has a water-riding main hull, said main hull having a nose anda step, said nose being located forward of said step; said fuselagehaving a tail extending rearwardly and upwardly away from said step saidaircraft has a tricycle undercarriage having a nose wheel and first andsecond main gear wheels; said nose wheel is mounted in said water-ridingmain hull of said fuselage; and said first and second main gear aremounted in respective first and second shoes, said first and secondshoes being located laterally to either side of said fuselage, saidfirst and second shoes including respective first and secondwater-riding hulls.
 18. The amphibious aircraft of claim 17 wherein aportion of said first main gear wheel protrudes downwardly of said firstshoe, and a portion of said second main gear wheel protrudes downwardlyof said second shoe.
 19. The amphibious aircraft of claim 17 whereinsaid main gear wheels are movable between a retracted position and anextended position, and in each of said extended and retracted positionssaid first and second main gear wheels protrude partially from saidrespective first and second shoes.
 20. The amphibious aircraft of claim17 wherein said fuselage has first and second sponsons extending toeither side thereof, each of said first and second water riding hulls ismounted to a respective one of said sponsons, and each of said first andsecond water-riding hulls has a keel.